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首页> 外文期刊>Chemistry: A European journal >Magnetic Relaxation in Single-Electron Single-Ion Cerium(III) Magnets: Insights from Ab Initio Calculations
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Magnetic Relaxation in Single-Electron Single-Ion Cerium(III) Magnets: Insights from Ab Initio Calculations

机译：单电子单离子铈（III）磁体中的磁弛豫：从头算计算的真知灼见

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摘要

Detailed ab initio calculations were performed on two structurally different cerium(III) single-molecule magnets (SMMs) to probe the origin of magnetic anisotropy and to understand the mechanism of magnetic relaxations. The complexes [Ce-III{Zn-II(L)}(2)(MeOH)]BPh4 (1) and [Li(dme)(3)][Ce-III(cot)(2)] (1; L=N,N,O,O-tetradentate Schiff base ligand; 2; DME=dimethoxyethane, COT=1,4-bis(trimethylsilyl)cyclooctatetraenyldianion), which are reported to be zero-field and field-induced SMMs with effective barrier heights of 21.2 and 30K respectively, were chosen as examples. CASSCF+RASSI/SINGLE_ANISO calculations unequivocally suggest that m(J)|+/- 5/2 and |+/- 1/2 are the ground states for complexes 1 and 2, respectively. The origin of these differences is rooted back to the nature of the ligand field and the symmetry around the cerium(III) ions. Ab initio magnetisation blockade barriers constructed for complexes 1 and 2 expose a contrasting energy-level pattern with significant quantum tunnelling of magnetisation between the ground state Kramers doublet in complex 2. Calculations performed on several model complexes stress the need for a suitable ligand environment and high symmetry around the cerium(III) ions to obtain a large effective barrier.
机译：详细的从头计算是在两个结构不同的铈（III）单分子磁体（SMM）上进行的，以探测磁各向异性的起源并了解磁弛豫的机理。配合物[Ce-III {Zn-II（L）}（2）（MeOH）] BPh4（1）和[Li（dme）（3）] [Ce-III（cot）（2）]（1; L ＝ N，N，O，O-四齿席夫碱配体; 2; DME ＝二甲氧基乙烷，COT ＝ 1，4-双（三甲基甲硅烷基）环辛酸酯基二烯二酸），据报道是零场和场诱导的具有有效势垒高度的SMM。分别选择21.2和30K的像素作为示例。 CASSCF + RASSI / SINGLE_ANISO计算明确表明m（J）| +/- 5/2和| +/- 1/2分别是配合物1和2的基态。这些差异的根源可以追溯到配体场的性质以及铈（III）离子周围的对称性。为配合物1和2构造的从头算起的磁化阻挡层，在配合物2的基态Kramers doublet之间存在显着的磁化量子隧穿，形成了对比的能级图。对几种模型配合物进行的计算强调了对合适的配体环境的要求铈（III）离子周围的对称性以获得较大的有效势垒。

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